While ASOC has a three level hierarchical structure based on separation at the division, subdivision and group level, NOI ranks offences only at the most detailed group level of ASOC (four digit code) categories.

Treatment of supplementary codes within NOI

Given that supplementary codes exist to cater for situations where there is insufficient information available to accurately code to any of the ASOC groups, the accuracy of a seriousness ranking that includes all these codes is likely to be diminished. As a result, not all supplementary ASOC codes were assigned a NOI ranking.

A NOI ranking has been assigned to an ASOC supplementary code if all group level offences within the same ASOC subdivision and/or division hierarchy were co-located within NOI. Where a ranking has been assigned to a supplementary code, it immediately follows the lowest ranked ASOC group level offence within that same ASOC subdivision and/or division. As an example, Figure 1 below illustrates that all group level offences for ASOC Division 03 - Sexual assault and related offences are co-located with NOI (i.e. the NOI rankings are adjacent) and therefore the supplementary code 0300 - Sexual assault and related offences, n.e.c. has been assigned the NOI ranking immediately following the lowest ranked group level offence 0329 - Non-assaultive sexual offences n.e.c.

Conversely, a NOI ranking has not been assigned to an ASOC supplementary code if the group level offences of a particular subdivision or division hierarchy are spread throughout NOI rankings. For example, there is a significant difference in perceived seriousness between ASOC group level code 1011 - Import Illicit Drugs (ranked 14 in NOI), and 1042 - Use Illicit Drugs (ranked 125). Whilst supplementary codes at the subdivision level for illicit drug offences have been assigned throughout NOI, the supplementary code at the division level for illicit drugs (1000 - Illicit drug offences not further defined) have not been assigned a NOI ranking as the perceived seriousness cannot accurately be determined.

Application of this approach was considered for each ASOC supplementary code. In cases where the ASOC group level codes were not immediately adjacent, consideration was given to the types of offences that separated the relevant group level ASOC codes within the NOI rankings. Exceptions were made to this rule, provided the interleved groups were unlikely to co-occur and statistical outputs were unlikely to be affected.

Additionally, supplementary codes were not assigned a NOI ranking if a division comprised only one ASOC group code (e.g. Division 07 - Unlawful Entry with Intent).